<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        var flag = true;
        var num = 16;
        // 1 num
        for(var i = 2; i <= num / 2; i++){
            if(num % i === 0){
                flag = false;
            }
        }
        if(flag){
            console.log('质数')
        }else{
            console.log('不是一个质数')
        }

       


    </script>
</body>
</html>